A teardrop tattoo (in the American prison system anyway) means, quite simply that you have murdered someone. For every teardrop you have symbolizes another victim.
It WAS adapted however from an old Russian custom of Ruskie prisoners getting them for a myriad of different reasons (from murder to the loss of a loved one, all the way up to the sexual domination of another prisoner) and circumstances.
The teardrop tattoo has different meanings.
The teardrop tattoo or tear tattoo is a symbolic tattoo that is placed underneath the eye. This tattoo originated with Chicano gangs in California. The meaning was that the wearer had killed someone.
the tear drop tattoo has had many different meanings. When they were first worn they meant that the wearer had been incarcerated and or killed someone while in or out of prison. As times have changed however, the teardrop has come to symbolize a friend or fellow gang member or family member that has died while the wearer is incarcerated.